like silver purified in a furnace on the earth, refined seven times

Yahweh's words are compared to silver that has been purified. AT: "they are without any imperfection" (See: rc://en/ta/man/translate/figs-simile)

You keep them

"You keep the righteous people safe"

"surround us"

This can be stated in active form. AT: "when people everywhere are praising evil" (See: rc://en/ta/man/translate/figs-activepassive)

"human beings" or "people"